Question: If $4a + 7b + 4c = 4$ and $x + 9y + 3z = -2$, what is $-20c - 35b - 20a + 30z + 90y + 10x$ ?
Explanation: $= -20a - 35b - 20c + 10x + 90y + 30z$ $= (-5) \cdot (4a + 7b + 4c) + (10) \cdot (x + 9y + 3z)$ $= (-5) \cdot (4) + (10) \cdot (-2)$ $= -20 - 20$ $= -40$